diff --git a/ovsdb/api/src/main/java/org/onosproject/ovsdb/controller/OvsdbEventSubject.java b/ovsdb/api/src/main/java/org/onosproject/ovsdb/controller/OvsdbEventSubject.java
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+++ b/ovsdb/api/src/main/java/org/onosproject/ovsdb/controller/OvsdbEventSubject.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.ovsdb.controller;
+
+import java.util.Set;
+
+import org.onlab.packet.IpAddress;
+import org.onlab.packet.MacAddress;
+
+/**
+ * Represents for a entity that carry important information for listener.
+ */
+public interface OvsdbEventSubject extends EventSubject {
+    /**
+     * Returns the MAC address associated with this host (NIC).
+     *
+     * @return the MAC address of this host
+     */
+    MacAddress hwAddress();
+
+    /**
+     * Returns the IP address associated with this host's MAC.
+     *
+     * @return host IP address
+     */
+    Set<IpAddress> ipAddress();
+
+    /**
+     * Returns the Port name associated with the host.
+     *
+     * @return port name
+     */
+    OvsdbPortName portName();
+
+    /**
+     * Returns the Port number associated with the host.
+     *
+     * @return port number
+     */
+    OvsdbPortNumber portNumber();
+
+    /**
+     * Returns the Port type associated with the host.
+     *
+     * @return port type
+     */
+    OvsdbPortType portType();
+
+    /**
+     * Returns the Ovs dpid associated with the host.
+     *
+     * @return Ovs dpid
+     */
+    OvsdbDatapathId dpid();
+
+    /**
+     * Returns the vm ifaceid associated with the host.
+     *
+     * @return vm ifaceid
+     */
+    OvsdbIfaceId ifaceid();
+}